An artificial heart device which contains fluted flow chambers, a heater, and devices for producing sound waves, electromagnetic radiation, pressure pulses, and magnetic lines of flux.
Mechanical pumps and other circulatory support devices are being developed and utilized to replace or augment biological hearts in animals and humans. These devices are intended to replace or support damaged or diseased hearts and have proven capable of sustaining experimental animals and humans for various periods.
Various parameters of blood flow and heart action are important to long-term patient survival. For example, the heart produces a pulsing biomagnetic field in the space around the body that can be measured by the magnetocardiogram. While these pulsing biomagnetic fields are being increasingly utilized for diagnostic purposes, these fields also have physiological significance for the functioning of the organism as a whole.
It is known that natural hearts produce a variety of energetic pulsations. Some of these, such as the sound, electrical, and pressure pulses, measured respectively with the stethoscope or phonocardiogrph, electrocardiogram, and various pressure recording devices (manometers, kymograms, ballistocardiograms), are well understood and widely utilized as diagnostic indicators of heart and circulatory health. Less well known is the thermal or heat pulse produced by each contraction of the heart muscle.
Likewise, the pumping of the blood sets up important neural signals because of the operation of the aortic and carotid baroreceptor system.
While the focus of medical research and clinical practice has been on the utility of the various pulsations as diagnostic indicators, little attention has been given to the possibility that such energetic pulsations, electromagnetic, acoustic, photonic, thermal, mechanical, and so on, serve functional purposes in the overall economy and integration of organismal functioning. For example, a theory about the possible roles of the various energetic pulsations is disclosed in an article published in 1996 by L. G. Russek and G. E. Schwartz with the title xe2x80x9cEnergy Cardiology: A Dynamical Energy Systems Approach for Integrating Conventional and Alternative Medicinexe2x80x9d published in xe2x80x9cAdvances: The Journal of Mind-Body Health,xe2x80x9d in Volume 12 on pages 4-24. Russek and Schwartz refer to the circulatory system and the blood flowing through it as a xe2x80x9cdynamical energy systemxe2x80x9d that communicates information throughout the body, to every cell, integrating a variety of system-wide processes. Implicit in this model is the role of the blood as a systemic communication system by virtue of its high conductivity for electrical, mechanical, acoustic, and other energetic pulsations. Hence the vibratory properties of the circulation are conceived by Russek and Schwartz to form a dynamical system with a variety of regulatory roles. Research by others, to be cited below, supports this view.
It is recognized that complications associated with cardiac assist and replacement devices are multifaceted, and include multisystem organ failure, as is disclosed in a book edited by E Braunwald, D P Zipes and P Libby with the title xe2x80x9cHeart Disease, A textbook of cardiovascular medicinexe2x80x9d 6th edition, published by W B Saunders Company in Philadelphia on page 609 of Volume I. The prevalence of systemic complications following implantation of partial or total artificial heart devices is indicative of deficiencies that need to be overcome.
Systemic complications from the use of artificial hearts are also supportive of the dynamical energy theory developed by Russek and Schwartz and referenced above. Specifically, the Russek and Schwartz theory has implications for heart replacement therapies because it points toward the heart as a fundamental dynamic synchronizer producing rhythmic information that affects diverse systems. Failures of artificial cardiac support systems to maintain life for extended periods may be a reflection of disturbances in the cardiac coordination system postulated by Russek and Schwartz.
These concepts and observations also have implications for the patient with a weakened or damaged or diseased heart. Heart failure, for example, has a variety of systemic consequences, some of which obviously arise from decreased perfusion of various organs and tissues, and some of which may arise from changes in other physical characteristics of the blood flow addressed by this patent.
Understanding of the significance of the electrical signals generated by the heart has been expanded by recent discoveries concerning the frequency spectrum of the electrocardiogram and the corresponding biomagnetic spectrum as recorded with the magnetocardiogram. This information is cited here because an implanted artificial heart will obviously not produce an electrocardiogram or magnetocardiogram of a healthy, natural heart, and will be deficient in other energetic pulsations and rhythms as mentioned above, and these deficiencies could have local and systemic implications and affect long term patient survival.
Specifically, heart rate variability, measured with the electrocardiogram, can be converted mathematically into power spectral density, a widely used non-invasive clinical test of integrated neurocardiac functioning, as disclosed by Z Ori, G Monir, J Weiss, X Sayhouni and D H Singer in an article published in 1992 with the title, xe2x80x9cHeart rate variability: Frequency domain analysisxe2x80x9d published in Cardiology Clinics Volume 10 Number 3 on pages 499-537. These authors disclosed that heart rate variability distinguishes between sympathetic and parasympathetic regulation of the SA node. Subsequent research showed that heart rate variability is a predictor of a wide range of parameters, including mortality following myocardial infarction (as disclosed by R E Kleiger and J P Miller in 1978 in an article entitled xe2x80x9cDecreased heart rate variability and its association with increased mortality after acute myocardial infarctionxe2x80x9d published in the American Journal of Cardiology Volume 59, pages 256-262, as well as in a 1998 paper by M T La Rovere, J T Bigger F I Marcus, A Mortara, P J Schwartz and ATRAMI Investigators entitled xe2x80x9cBaroreflex sensitivity and heart-rate variability in prediction of total cardiac mortality after myocardial infarctionxe2x80x9d published in Lancet Volume 351, Number 9101 on pages 478-484), congestive heart failure (as disclosed in an article by P Saul, Y Arai, R Berger, L Lilly, W Colucci, and R Cohen published in 1988 with the title xe2x80x9cAssessment of autonomic regulation in congestive heart failure by heart rate spectral analysisxe2x80x9d published in the American Journal of Cardiology Volume 61 on pages 1292-1299), and coronary angiography (as disclosed by M W Saini et al. in 1988 in an article entitled xe2x80x9cCorrelation of heart rate variability with clinical and angiographic variables and late mortality after coronary angiographyxe2x80x9d published in the American Journal of Cardiology Volume 62 on pages 714-717). Heart rate variability is also predictive of rejection risk following transplantation (as disclosed by T Binder, B Frey, G Porenta, G Heinz, M Wutte, G Kreiner, H Gossinger, H Schmidinger, R Pacher, and H Weber in 1992 in an article entitled xe2x80x9cPrognostic valve of heart rate variability in patients awaiting cardiac transplantationxe2x80x9d published in Pacing and Clinical Electrophysiology Volume 15 on pages 2215-2220), it characterizes psychological illnesses including major depression (disclosed in 1991 by V. K. Yeragani et al. xe2x80x9cHeart rate variability in patients with major depressionxe2x80x9d published in Psychiatric Research Volume 37 on pages 35-46) and panic disorders (as disclosed in an article by V K Yeragani, R Pohl, R Berger, R Balon, C Ramesh, D Glitz, K Srinivasan and P Weinberg entitled xe2x80x9cDecreased HRV in panic disorder patients: a study of power-spectral analysis of heart ratexe2x80x9d published in Psychiatric Research Volume 46 on pages 89-13), autonomic changes associated with hostility (as disclosed by R P Sloan, P A Shapiro, J T Bigger, E Bagiella, R C Steinman, and J M Gorman in an article published in 1994 with the title xe2x80x9cCardiac autonomic control and hostility in healthy subjectsxe2x80x9d published in the American Journal of Cardiology Volume 74 on pages 298-300), and risk from hypertension (as disclosed in a 1993 article by J H Markovitz, K A Matthews, W B Kannel, and J L Cobb entitled xe2x80x9cPsychological predictors of hypertension in the Framingham study: is there tension in hypertension?xe2x80x9d published in the Journal of the American Medical Association Volume 270 Number 20 on pages 2439-2494).
The implication of these findings is that a normal electrocardiogram, providing normal rate variability and normal electrocardiographic signatures, as well as providing normal energetic pulsations of other kinds mentioned above, can be correlated with a wide range of important systemic physiological and emotional attributes.
Additional extensive research on heart rate variability, its physiological and pathophysiological interpretations, and clinical applications will be found in a book with 66 contributing authors edited by M Malik and A J Camm published in 1995 with the title xe2x80x9cHeart Rate Variabilityxe2x80x9d and published by Futura Publishing Company. Also see a book edited by M. Di Rienzo, et. al. published in 1999 with the title, xe2x80x9cMethodology and clinical applications of blood pressure and heart rate analysisxe2x80x9d published in Amsterdam by IOS press. See also the book by R Takalo entitled xe2x80x9cVariability of Blood Pressure and Heart Rate in Borderline and Mild Hypertension: With Special Reference to Spectral Analysisxe2x80x9d published by Uppsala Universitet, 1999.
In 1995, R McCraty, M Atkinson, W A Tiller, G Rein and A D Watkins disclosed relationships between emotional state and the power spectrum of the heart rate variability, as described in an article entitled xe2x80x9cThe effects of emotions on short-term power spectrum analysis of heart rate variabilityxe2x80x9d published in The American Journal of Cardiology in Volume 76, Number 14, on pages 1089-1093. Regular variations in heart rate and electrocardiographic recordings are correlated with a whole-body state referred to as xe2x80x9ccoherence,xe2x80x9d a state reflecting a balance between the rhythms of the sympathetic and parasympathetic branches of the autonomic nervous system that regulate the heart rate. This beneficial balanced state is associated with a coupling, or entrainment, or phase-locking of a variety of electrical and mechanical rhythms, including the heart, respiration, autonomics, and the baroreceptor feedback loop to the brain. The studies implicate the heart electricity, as measured by the electrocardiogram, as a systemic synchronizer of these various rhythmic processes.
Moreover, the heart generates the largest pulsing biomagnetic field of the body, which can be detected in the space around the body with a coil and/or with a superconducting quantum interference device (SQUID) as disclosed by D Cohen in 1967 in an article entitled xe2x80x9cMagnetic fields around the torso: production by electrical activity of the human heartxe2x80x9d published in Science Volume 156, pages 652-654, and also disclosed by D Cohen, E A Edelsack and J E Zimmerman in 1970 in an article entitled xe2x80x9cMagnetocardiograms taken inside a shielded room with a superconducting point-contact magnetometerxe2x80x9d published in Applied Physics Letters Volume 16, pages 278-280. This discovery is important because there is evidence that cellular regulations and healing processes in general can be influenced by low frequency pulsing electromagnetic fields as disclosed by B F Sisken and J Walker in 1995 in an article entitled xe2x80x9cTherapeutic aspects of electromagnetic fields for soft-tissue healingxe2x80x9d published in a book edited by M Blank entitled xe2x80x9cElectromagnetic fields: biological interactions and mechanismsxe2x80x9d published in Advances in Chemistry Series 250, American Chemical Society, Washington, D.C., on pages 277-285, and in an article by C A L. Bassett published in 1995 with the title xe2x80x9cBioelectromagnetics in the service of medicinexe2x80x9d published in a book edited by M Blank with the title xe2x80x9cElectromagnetic fields: biological interactions and mechanismsxe2x80x9d published in Advances in Chemistry Series 250, American Chemical Society, Washington, D.C. on pages 261-275.
Some have argued that the energy contained in the electrocardiograms and magnetoencephalograms must be far too weak relative to ambient and internal noise to produce significant physiological or emotional effects on cells and tissues and organs a distance away from the source. However, recent research has shown that the noise in a biological system can play a constructive role in the detection and utilization of weak rhythmic signals by a nonlinear cooperative effect known as stochastic resonance. In essence, a regular periodic signal can entrain ambient noise to boost the signal to a level above the threshold value, enabling it to generate measurable effects on cellular activities. Stochastic resonance has been firmly established as a valid phenomenon in a wide range of sensory and neural systems and is being exploited in electronic equipment, as disclosed by K Wiesenfeld and F Moss in 1995 in an article entitled xe2x80x9cStochastic resonance and the benefits of noise: from ice ages to crayfish and SQUIDsxe2x80x9d published in Nature, Volume 373, pages 33-36 and in an article by A R Bulsara and L Gammaitoni in 1996 with the title xe2x80x9cTuning into noisexe2x80x9d published in Physics Today, March issue, pages 39-45. All of these concepts strengthen our assertion that the various energetic pulsations produced by the biological heart can have constructive effects throughout the body, and that their absence in the patient with an implanted artificial heart can have deleterious consequences.
Another attribute of blood flow is its rheological characteristics, which will obviously not be the same for an artificial mechanical heart compared with a biological heart. The importance of mechanical impulses in cardiac assist devices is documented in a paper by S M Mehta, T X Aufiero, W E Pae Jr et al, 1996, entitled xe2x80x9cResults of mechanical ventricular assistance for the treatment of post cardiotomy cardiogenic shockxe2x80x9d published in American Society for Artificial Internal Organs Journal Volume 42, p. 211. These authors found that postimplant hemorrhage occurs more frequently in patients supported with a ventricular assist device with a centrifugal pump than in patients supported with a pulsatile pumping device for the same indication, postcardiotomy cardiogenic shock.
Pulsatile and nonpulsatile blood flow have been compared by A xc3x9cndar, N Henderson, G B Thurston, T Masai, E A Beyer, O H Frazier, and C D Fraser Jr. in a 1999 report in an article with the title xe2x80x9cThe effects of pulsatile versus nonpulsatile perfusion on blood viscoelasticity before and after deep hypothermic circulatory arrest in a neonatal piglet modelxe2x80x9d published in Artificial Organs Volume 23 Number 8, pages 717-721. These authors found that the pulsatile pump system produces less blood trauma than the standard nonpulsatile roller pump as indicated by lower values of both viscosity and elasticity during cardiopulmonary bypass. Blood trauma increases blood viscoelasticity by increasing red cell aggregation and plasma viscosity and by decreasing cell deformability.
There has been debate over the effectiveness of pulsatile versus nonpulsatile perfusion, but there are clear physiological benefits of pulsatile perfusion during cardiopulmonary bypass compared to nonpulsatile perfusion, as disclosed by A Undar, A J Lodge, C W Daggett, T M Runge, R M Ungerleider, and J H Calhoon in 1998 in an article entitled xe2x80x9cThe type of aortic cannula and membrane oxygenator affect the pulsatile waveform morphology produced by a neonate-infant cardiopulmonary bypass system in vivoxe2x80x9d published in Artificial Organs Volume 22 number 8 on pages 681-686.
In 1932, J. Bremer described the xe2x80x9cpresence and influence of spiral streams in the heart of the chick embryoxe2x80x9d in an article published in the American Journal of Anatomy in Volume 49, on pages 409-440. Bremer disclosed that, in the chick embryo of about forty-hours and older, xe2x80x9cthe two streams, definitely right and left as they flow down the atrioventricular canal, can be followed through the ventricles.xe2x80x9d Bremer also listed earlier authors who had noted this phenomenon.
In 1973, D E M Taylor and J D Wade disclosed the results of cineradiography with fine stream dye injection, in an article entitled xe2x80x9cPattern of blood flow within the heart: a stable systemxe2x80x9d published in Cardiovascular Research, Volume 7, pages 14-21. They noted that the flow patterns within the cardiac ventricles during diastolic filling in dogs and sheep are expanding vortex systems behind the cusps of the mitral and tricuspid valves.
In 1981, B L Langille and S L Adamson authored a paper entitled xe2x80x9cRelationship between blood flow direction and endothelial cell orientation at arterial branch sites in rabbits and micexe2x80x9d that was published in Circulation Research in Volume 48 on pages 481-488. In this paper the authors disclosed that the patterns of orientation of endothelial cells near arterial branch sites were almost identical to the orientation of the flow streamlines near the vessel walls. In their article, Langille and Adamson summarized the work of others indicating that flow-induced alterations in endothelial cells may be a factor in atherosclerosis. They also summarized research of others indicating that the shape and orientation of endothelial cells is determined by blood flow characteristics.
In 1983, B. S. Massey disclosed that counter-rotating helices tend to develop at simple pipe bends, in his book entitled, xe2x80x9cMechanics of fluidsxe2x80x9d published by Van Nostrand Reinhold in the United Kingdom, on pages 222-224.
In 1984, Y. C. Fung disclosed that the heart is twisted on its axis and the aortic arch is tapered, curved, and twisted, in his book entitled xe2x80x9cBiodynamics: circulationxe2x80x9d, published by Springer-Verlag, on pages 77-164.
In 1991, P A Stonebridge and C M Brophy disclosed that fiber-optic angioscopic examination shows xe2x80x9cthat the inner surface of blood vessels is often not smooth but organized in a series of spiral foldsxe2x80x9d in their article entitled xe2x80x9cSpiral laminar flow in arteries?xe2x80x9d published in The Lancet in Volume 338 on pages 1360-1361. These authors described a number of observations indicating that xe2x80x9cspiral blood flow is a normal process, at least in parts of the circulation.xe2x80x9d
Kilner et al, 1993 disclose the xe2x80x9cHelical and retrograde secondary flow patterns in the aortic arch studied by three-directional magnetic resonance velocity mappingxe2x80x9d published in Circulation in Volume 88 (part 1) on pages 2235-2247. Right-handed helical flows predominate in the upper aortic arch in late systole, with end-systolic retrograde flow along inner wall curvatures. These consistent features of intra-aortic flow in healthy subjects arose, in part, from the curvature of the arch and the pulsatility of flow in it.
Finally, rhythmic operation of the baroreflex system has implications for systemic circulation via the vasomotor center in the medulla, which regulates heart rate and vasodilation/vasoconstriction throughout the body. Obviously a nonpulsatile cardiac assist device or artificial heart or a failing heart will not provide the rapid rhythmic pulsations in blood pressure and consequent neural impulses in nerves ascending from the aortic and carotid baroreceptors, and this will have systemic consequences. Moreover, there is evidence that the timing of the baroreflex pulsations in relation to the cardiac and respiratory rhythms has systemic physiological and emotional effects, and the present invention acknowledges these relationships by including means for optimizing them.
Extensive research and prior art relates to cardiac assist devices, artificial hearts, artificial prosthetic conduits, and artificial or replacement valves for such devices. Additional art relates to rhythmic processes, their relationships, and the therapeutic significance of appropriate rhythmic timing.
Key to the deployment of long-term implantable cardiac devices is the development of bio-compatible materials and conduits that do not allow for the formation of blood stagnation or stasis volumes or sites for bacterial growth and infection that are hidden from the patient""s immune system and that do not introduce or allow the entry of bacterial or other contamination into the patient""s body or circulatory system. This biocompatible materials should have a minimum of blood-contacting material-surface transitions that can become misaligned and thereby introduce turbulence to the flow, but should not have differing degrees of surface properties that provide an opportunity for biological interfaces forming on such surfaces clot or to slough off to become emboli in the circulating blood. The bio-compatible materials should also provide for changing dimensions of conduits as blood pulses through them or as materials change dimensions over weeks or months after implantation into the body.
Thus, U.S. Pat. No. 5,810,708 (xe2x80x9cVentricular assist conduit with externally supported tissue valvexe2x80x9d) discloses xe2x80x9ca valved blood conduit having woven and/or knitted filamentary fabric walls which are impregnated outwardly with a biologically-compatible impermeable material so that the conduit walls are impermeable to blood, while the inner surface of the conduit wall remains textured or porous to promote the growth of a stable biological interface. Provision is made for sealingly connecting the valved blood conduit to other blood-carrying components without disruption of smooth and stasis-free blood flow. The connecting provisions also minimize the number of blood-contacting material-surface transitions, and provide for accommodation without loss of sealing integrity of dimensional changes which will occur at the connections after implantation of the valved conduit and assist device. These dimensional changes will occur as a transitional collagen or other biodegradable coating of the conduit is absorbed, as components of the valved conduit and adjacent structure take a set with the passage of time after surgical implantation, and as a biological interface is formed on the blood-contacting surfaces by the host""s circulatory system.xe2x80x9d The wall of the conduit is preferably composed of xe2x80x9ca single ply of tubular-woven and/or knitted polyethylene terephthalate fabric . . . transfer-coated externally with sheet silicone rubber material . . . so that it forms a liquid-impermeable barrier or membrane integral with the fabric . . . producing a porous inner surface into which a stable biological interface may implant.xe2x80x9d The result is a conduit with a single unitary blood-contacting flexible wall without the use of gaskets or other sealing devices which are exposed to the flowing blood. The entire disclosure of this United States patent application is hereby incorporated by reference into this specification.
Incorporation of valves in a blood conduit requires consideration of prior art relating to artificial prostheses as substitutes for valves in the human heart. U.S. Pat. No. 6,228,112, xe2x80x9cArtificial heart valve without a hinge,xe2x80x9d discloses prior art valves which, by their construction and design, impede blood flow and can create stagnation that can lead to thrombosis, and which, in some cases, have hinges that can malfunction. The invention described in U.S. Pat. No. 6,228,112 overcomes these prior art limitations with a valve structure without hinges. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
Of particular importance when considering valvular structures in the circulation is the problem of wear. Worn out valves present hazards to the patient, not the least of which is the higher operative mortality rate associated with second and third reoperations to replace worn out valves. While artificial materials can be manufactured into valves that do not wear out and consequently do not require replacement, bioprosthetic or tissue valves are often preferred because of their better biocompatibility. Blood can adhere and clot on mechanical valves, requiring that the patient be continually treated with anticoagulants. However, these treatments have risks of their own, including bleeding and thromboembolism. These drawbacks and other problems with the prior art are discussed and resolved in U.S. patent application Ser. No. 20010002445 xe2x80x9cBioprosthetic cardiovascular system,xe2x80x9d which teaches a method of building valves that can be routinely removed when they begin to fail and then replaced using catheter-based endovascular procedures or minimally invasive surgery, with low attendant morbidity. The patent application teaches a valve design that is sufficiently collapsible so as to be able to be passed through the lumen of a catheter inserted into the femoral artery or other large vessel. The collapsed valve is re-expanded to fit into a permanent housing or base unit installed in the patient""s heart. The valve can be collapsed again for removal once the valve wears out. While a variety of materials are available, the cited invention utilizes valve leaflets constructed from sheets of chemically preserved bovine pericardium. The entire disclosure of this United States patent application is hereby incorporated by reference into this specification.
The optimal timing of the various rhythmic process in relation to one another (heart, respiration, baroreflexes) is the subject of considerable research and prior art. Thus, U.S. Pat. No. 5,997,482, entitled xe2x80x9cTherapeutic method for a human subjectxe2x80x9d discloses xe2x80x9ca therapeutic method for a human subject which determines an optimal relationship between respiratory frequency and heartbeat unique for any given patient by utilizing Fourier analysis.xe2x80x9d In particular, U.S. Pat. No. 5,997,482 describes the benefits of high amplitude low-frequency harmonic oscillations in the heart rate, in the frequency range of 0.01-0.14 Hertz, that are xe2x80x9cassociated with a tendency to decrease psycho-emotional strain, reduced tiredness and reduced chronic agitation (see also a 1983 article by E. G. Vashillo et al entitled xe2x80x9cResearch of Resonance Characteristics of a Cardiovascular systemxe2x80x9d published in the U.S.S.R Academy volume 257). Within the specified frequency range, xe2x80x9cevery individual has a unique xe2x80x98resonancexe2x80x99 frequency which, when these oscillations reach their highest amplitude, the patient recognizes a general well being and improvement in a variety of therapeutic conditions.xe2x80x9d The therapeutic method employed in U.S. Pat. No. 5,997,482 involves registering a subject""s current respiration rate and converting it into a first electrical signal, registering a current heartbeat of the subject and converting it into a second electrical signal, spectrally analyzing the first and second electrical signals to generate a resulting signal corresponding to a phase shift there between. In U.S. Pat. No. 5,997,482, biofeedback is used to maximize and maintain the ideal resonance relationships between rhythms, with a zero or minimum phase shift between the heart and breath oscillations. Positive impacts of maintaining these rhythmic relationships are: pulse rate decreases to an average 7-10 beats per minute among children and to 5-6 beats per minute among athletes, arterial pressure is normalized, the blood circulation in peripheral parts of the body improves, and the speed of voluntary muscle relaxation increases. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.
The method of U.S. Pat. No. 5,997,482 has been used to treat bronchial asthma, neuroses, heart rate disorders, and disorders of the autonomic nervous system. The method is designed to decrease psychological tension. The method facilitates the well-researched phenomenon of the xe2x80x9crelaxation responsexe2x80x9d with its plurality of physiological and psychological benefits.
Related art discusses the rhythms of the baroreflex arc, which are particularly relevant to heart failure. A patient""s responses to this disorder are complex and include involvement of the sympathetic nervous system, the renin-angiotensin system, and other neuroendocrine systems, all affecting the peripheral vasculature. The baroreflex system provides partial control of the heart rate and peripheral vasculature. The baroreceptors in the aorta and carotid arteries respond to increases or decreases in arterial blood pressure by firing more or less frequently. Nerves transmit these impulses to the brain which modifies heart rate and vasomotor tone throughout the body and affects the sympathetic/parasympathetic balance. Modulation of baroreflex activity by electrical stimulation of carotid sinus nerves has been used to treat hypertension and intractable angina pectoris.
Carotid sinus nerve stimulation has been developed by Medtronic, Inc., of Minneapolis, Minn. In the 1960s to early 1970s, Medtronic produced and marketed two carotid sinus nerve stimulators for treatment of hypertension, the xe2x80x9cBarostat,xe2x80x9d and angina, the xe2x80x9cAngistat.xe2x80x9d These devices lowered blood pressure, decreased myocardial work and oxygen consumption, alleviating hypertension and angina. Moreover, ischemia detection has been used to regulate baroreflex nerve stimulation in an implanted device as described in the international publication WO92/16257.
More recently, U.S. Pat. No. 6,073,048, entitled xe2x80x9cBaroreflex modulation with carotid sinus nerve stimulation for the treatment of heart failure,xe2x80x9d discloses a system and method for stimulating the baroreflex arc based on levels of indicators from the body, including heart activity and other indicators. This patent includes xe2x80x9ca system for coordinating the stimulation of nerves for controlling the level of neurohormonal activation in a living body having a heart subject to potential or actual pathologic stress levels comprising: an implantable pulse generator with a microprocessor and memory adapted and disposed to run a plurality of processes, a sensor for sensing and measuring the value of an indicator of SVR (systemic vascular resistance) in the body, adapted and disposed to provide readings to said microprocessor for use by said processes, a bradycardia pacer control process included within said pulse generator for pacing the heart when a condition of bradycardia is present so as to prevent insufficient heart rate by said heart, at least one stimulation electrode connected to effectively deliver electrical stimulation output to a baroreceptor nerve site, a process for monitoring heart rate and estimating SVR from said sensor in order to modify said stimulation output, a system wherein said process for estimating SVR increases said stimulation output at a predetermined level of estimated SVR and decreases said stimulation output at another predetermined level of estimated SVR, a system further comprising an activity sensor, wherein said process for estimating SVR comprises a check of the activity sensor level made before increasing said stimulation output, a system further comprising an additional process within said pulse generator wherein if the estimated SVR is not determined to be above a predetermined level nor below another predetermined level, said additional process determines whether pacing is needed, and if so provides for a decreased amount of said stimulation output, a system wherein if said activity sensor indicates strenuous exercise, said stimulation output is suspended for the duration such indication is present, a system further comprising an intracardiac electrode and an additional process within said pulse generator, wherein said additional process provides that said stimulation output is gated to electrocardiographic indicators of cardiac activity received by said intracardiac electrode, a system wherein said additional process provides comprises variable stimulation output settings and delay timing, a method of automatically optimizing the cardiovascular responsiveness of a patient for the patient""s condition through controlled application of electrical stimulation of nerves emanating from baroreceptors of said patient comprising: providing electrical stimulation to said nerves of sufficient intensity and duration so as to reduce neurohormonal activation and induce peripheral blood vessel dilation and a drop in heart rate, determining the responsiveness of the patient""s body to said stimulation by sensing a feedback parameter of patient""s responsiveness indicating altered cardiovascular function; and adjusting said electrical stimulation provided to the nerves based on said feedback and an optimization algorithm until the patient""s cardiovascular system is optimized for his/her condition, sensing activity of said patient using an activity sensor, and if said activity sensor indicates periods of activity, suspending or lowering intensity of said electrical stimulation until a period of time after the sensed activity has ceased.xe2x80x9d The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
U.S. Pat. No. 6,073,048 also discloses a method wherein, when an optimization algorithm is informed of overshoot in the drop in heart rate and/or peripheral vascular resistance, it responds by reducing the stimulation of the nerves arising from the baroreceptors; and, additionally, it also describes a method wherein, if overshoot of drop in heart rate passes a predetermined threshold, pacing the heart to maintain a predetermined heart rate. This patent also discloses a method of controlled application of electrical stimulation of nerves emanating from baroreceptors of said patient comprising: providing electrical stimulation to said nerves of sufficient intensity and duration so as to reduce neurohormonal activation and induce peripheral blood vessel dilation and a drop in heart rate, sensing activity of said patient using an activity sensor, and if said activity sensor indicates periods of activity, suspending or lowering intensity of said electrical stimulation until a period of time after the sensed activity has ceased. The process of this patent uses closed loop feedback techniques to improve baroreflex activity. It is potentially useful for patients with congestive heart failure including cases caused by coronary artery disease, myocardial infraction and chronic hypertension but not limited to these causes. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
U.S. Pat. No. 6,073,048 teaches that, in heart failure, inappropriate sympathetic nervous system activation causes vasoconstriction, neurohormonal stimulation, and increased systolic calcium. All of these factors contribute to a progression of the heart failure symptoms including cardiac arrhythmias and sudden death. Overdriving the central nervous system nerves with the invention of this patent can alleviate these factors. If the human sensor indicates stimulation is needed, stimulation commences and alleviates vasoconstriction which in turn decreases afterload, decreases myocardial energy expenditure, and prevents myocardial cell death. The stimulation also acts to decrease the prevalence of cardiac arrhythmias and to decrease cytosolic calcium levels, which in turn decreases chronotropy and inotropy, decreases cell energy expenditure and prevents cell death. Stimulation also decreases neurohormonal output which is inappropriately elevated in congestive heart failure and is associated with the reduction in cardiac output. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
It is an object of this invention to provide a device to record and store and restore or reintroduce to the blood flowing from an artificial heart or cardiac support device important pulsatile and flow characteristics that are absent when blood is caused to circulate by artificial means.
It is another object of this invention to provide a device for restoring certain physical characteristics of blood flow from a biological heart that has been compromised or weakened by damage or disease.
It is a further object of the invention is to provide a device adapted to reintroduce electromagnetic pulses to the blood emerging from artificial hearts or cardiac assist devices or to restore the strength and quality and timing of the electromagnetic pulses to blood emerging from a biological heart that has been compromised or weakened by damage or disease.
It is another object of the invention to provide a device adapted to reintroduce or strengthen the pattern of pulsing electromagnetic fields that a normal healthy heart radiates into the surrounding tissues and that gives rise to the normal electrocardiogram and magnetocardiogram.
It is yet another object of the invention to reintroduce acoustic pulses to the blood emerging from artificial hearts or cardiac assist devices or to restore the strength and quality of the acoustic pulses to blood emerging from a biological heart that has been compromised or weakened by damage or disease.
Another object of the invention is to provide an apparatus designed to reintroduce pressure pulses to the blood emerging from artificial hearts or cardiac assist devices or to restore the strength and quality of the pressure pulses to blood emerging from a biological heart that has been compromised or weakened by damage or disease.
A further object of the invention is to provide a device to reintroduce heat pulses to the blood emerging from artificial hearts or cardiac assist devices or to restore the strength and quality of the heat pulses to blood emerging from a biological heart that has been compromised or weakened by damage or disease.
Another object of the invention is to provide a device to reintroduce vortical or spiraling motions to the blood emerging from artificial hearts or cardiac assist devices that do not produce such flows or to restore the strength and quality of the vortical or spiraling motions to blood emerging from a biological heart that has been compromised or weakened by damage or disease.
Yet another object of the invention is to provide means for recording and storing various physical pulses produced during the operation of a healthy heart so said pulses can be recorded and reintroduced into a patient that is lacking or deficient in such pulsations for whatever reason.
In accordance with this invention, there is provided an implantable apparatus for treating a heart which is comprised a fluted flow chamber, means for recording the energy properties of a heart, means for imparting energy to the blood flowing through said heart wherein said energy is selected from the group consisting of thermal energy, acoustic energy, electromagnetic energy, magnetic energy, and mixtures thereof.